<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>css 热点动画</title>
</head> 
<style>
    .back {

        margin: 0 auto;
        width: 774px;
        height: 650px;
        background: no-repeat url(map.png);
        background-color: rgba(0,0,0,0.6);
    }
    .center {
        position: relative;
        left: 546px;
        top: 228px;
        width: 8px;
        height: 8px;
        background-color: cornflowerblue;
        border-radius: 50%;
    }
    .tw {
        left: 660px;
        top: 490px;
    }
    .gz {
        left: 545px;
        top: 526px;
    }
    .a1,.a2,.a3 {
        position: absolute;
        left: 50%;
        top: 50%;
        transform: translate(-50%,-50%);
        width: 6px;
        height: 6px;
        border: 2px solid cornflowerblue;
        border-radius: 50%;
        animation: a 1.2s linear infinite;
    } 
     .a2 {
         animation-delay: 0.4s;
     }
     .a3 {
         animation-delay: 0.8s;
     }
    @keyframes a {
        70% {
            width: 40px;
            height: 40px;
            opacity: 1;
        }
        100% {
            width: 70px;
            height: 70px;
            opacity: 0;
        }
    }
</style>
<body>
    <div class="back">
     <div class="center">
        <div class="a1"></div>
        <div class="a2"></div>
        <div class="a3"></div>
     </div>
     <div class="center tw">
        <div class="a1"></div>
        <div class="a2"></div>
        <div class="a3"></div>
     </div>
     <div class="center gz">
        <div class="a1"></div>
        <div class="a2"></div>
        <div class="a3"></div>
     </div>
    </div>
</body>
</html>